The instant disclosure relates generally to satellites. In particular, the instant disclosure relates to apparatus and methods for maintaining a satellite's position relative to other satellites in a satellite constellation.
A satellite constellation includes two or more satellites, each having a designated orbit. In order to maintain the services provided by the constellation, it may be desirable for satellites within the constellation to maintain prescribed positions relative to each other. These relative positions need not be fixed, but instead may vary with time according, for example, to a designated algorithm. Yet, because the relative positions of the satellites within the constellation are prescribed, maneuvering a satellite within the constellation—for example, to avoid collision with orbital debris—can result in a degradation in the constellation's performance.
Thus, the altitude, latitude, and longitude of satellites within a constellation are predictable as functions of time. As a result, satellites within a constellation are more vulnerable to debris collisions and/or hostile action (e.g., attack by hostile spacecraft or ground-based threats, such as lasers and anti-satellite missiles). Put another way, because satellites within a constellation cannot maneuver extensively without risking diminished performance, they cannot execute large longitude or latitude maneuvers or altitude changes to evade threats, whether those threats are passive (e.g., orbital debris) or deliberate (e.g., hostile action).